Upper Fort Garry originally featured four circular, stone bastions located at each of its corners. Each bastion was roughly 24 feet in diameter, and about 31 feet high with eaves of 24 feet. Bastions are tower-like constructions built at an angle to allow for defensive gunfire in multiple directions. The fort’s bastions had two floors and four military pieces each. By shooting through the broad gun ports, defenders could catch hostile forces in a cross fire. In the absence of such attacks the bastions were mainly used for storage between 1835 and 1845

In 1846, a group of soldiers called the 46th Regiment of Foot arrived in Red River. About 300 soldiers came to occupy about 80% of the fort’s space. The bastions were part of the many buildings repurposed during their stay. In addition to storage, the bastions were used as, from the southeast going clockwise: a guardhouse, the Sergeant Major’s living quarters, the canteen, and magazine – where military supplies and ammunition were stored.

During their stay, the soldiers maintained a continual watch from the bastion on top of the sales shop. Members of the Regiment patrolled along the gallery, a long, raised wooden walkway that ran along the inside of the fort. These patrols were supposed to monitor potential threats to the fort. George Simpson had won the British government’s approval of this military presence to deter American incursions across the border but, of course, it also helped the HBC to intimidate traders who were challenging the company’s monopoly.